Hot stamping is the heat transfer of a pigmented color or metallized surface from a polyester carrier onto a thermoplastic substrate. A heated die or roller is used to apply pressure to the hot stamping foil. The pressure forces the pigmented or metallized portion of foil into contact with the plastic substrate. The combination of heat and pressure softens the plastic substrate and activates the foil, causing it to adhere to the substrate. When the foil is removed, only the area subjected to the hot stamp remain affixed to the plastic substrate. A vertical stamping or roll-on machine is used for the operation. The vertical stamping machine contains a heated die of brass, steel or silicone rubber to transfer an area of a specific pattern as each part is place into position. Roll-on methods utilize a silicone rubber roller or arced die to apply the foil in a continuous or batch process. Heat transfer can be achieved at temperatures of about 107.degree. C.
Hot stamping is an efficient, inexpensive way to apply decoration to thermoplastic substrates. Hot stamping cannot be used with glass because glass melts at a much higher temperature than most thermoplastic materials.
Generally decoration in the form of gold or silver leaf, color design or printing is applied to glass by a glazing process similar to that used with ceramics. The colored or metallic ink decoration is applied to the glass container by a variety of methods such as silk screen, printing, etc. The container is then subjected to extremely high kiln temperatures and the decoration is, in essence, baked on. Unfortunately this process is time consuming, expensive, energy intensive, and subject to safety considerations due to the high temperatures and gases necessary to operate the kilns.
There is thus a great need for a simple, economical and ultra-safe procedure for applying decoration to glass substrates.